Hydration and fluid requirements

Water is an essential requirement for the body and is our most important nutrient. It makes up around two-thirds of our body. The body needs fluid for a wide range of functions, including metabolism, blood circulation, regulating body temperature and blood pressure, maintaining brain function, removing waste products and keeping the skin hydrated. This article aims to inform you more about the particular importance of ensuring you drink enough fluid while following a Slim & Save plan.

The term ‘fluid’ includes not only water from the tap or in a bottle but also other drinks that provide water such as tea, coffee, milk, fruit juices and soft drinks. However, for this article, we will be referring to the water that is recommended as part of the programme.

Why is water intake particularly crucial on our programmes?

When you consume a regular diet (without restricting carbohydrate intake to the point of inducing ketosis), your body stores glycogen in the liver and muscles as the body’s short-term energy storage system, each gram of glycogen is attached to approximately to 4 grams of water. When in ketosis (as with our programmes), you lose this glycogen storage and its associated water, making you more vulnerable to dehydration.

What role does water have in our body?

Removal of waste products – Drinking plenty of water enables you to maintain a healthy level of body water content to replace the natural water loss filtered by the kidneys, in the form healthy urine production to remove waste products. The liver and kidneys work together to remove waste products (or toxins) from the body. For example, the metabolism of protein (which happens in the liver) produces waste products (ammonia, uric acid, urea and creatinine) which are filtered out by the kidneys and removed through our urine. If you don’t drink enough water, your body’s reaction is to reduce urine output to try to conserve water. The role of the liver may also be affected by not drinking enough, and there may be a build up of waste products. As our programmes are high in protein, drinking plenty is especially important.

Blood circulation – Water is essential for proper circulation of blood around the body. Blood carries vital nutrients such as oxygen to the body’s cells. If you don’t drink enough, the amount of blood circulating through your body (blood volume) will reduce. This, in turn, can affect the levels of oxygen in the bloodstream and make you feel more tired. Getting enough oxygen to your cells is also important in helping your body to break down (metabolise) fats into energy efficiently.

Brain function – Being well hydrated can also affect our brain function. Research has found that even mild dehydration can cause a reduction in attention and can affect the mood. Drinking enough fluid can help keep headaches at bay.

Healthy digestion – Water is essential to maintaining healthy digestion of your food and also prevents constipation. Water encourages the passage of waste through your digestive system and helps soften your poo. The fibre in your diet (e.g. from vegetables) acts like a sponge, absorbing water. Without adequate fluid, the fibre you eat can’t do its job properly, and you’re more likely to suffer from constipation.

Skin and body tissue health – Water is essential for maintaining healthy skin. Water helps to moisturise your skin from the inside out. Good hydration helps to keep your skin fresh, soft and smooth and helps get rid of wrinkles by plumping up the skin. Although, due to the challenges of carrying out good quality research in this area, there is only limited evidence to back up the importance of water on the skin. However, some studies have also suggested that prolonged dehydration can also be linked to hair loss. The mechanism of this is unclear but may be related to insufficient fluids being available to carry proteins and other nutrients to the scalp.

How much water should I be drinking?

Although you’re likely to feel thirstier on our programmes, don’t just be guided by your thirst. Make sure you drink plenty. You will need to drink around 2-3 litres every day, but as your water requirement will be individual to you, we have produced a handy automated tool to help you to work out your individual water requirement which you can find here.

Drinking more water as part of the programme is also a great way to get your body used to drinking water as your main choice of fluid, and help you to establish healthier drinking habits for the long term. Water is free and delivers fluid without calories or the sugars that can potentially damage teeth.

Written by Annemarie Aburrow RD BSc (Hons) PGDip, Slim & Save Dietitian.

How much water do you drink each day? Do you feel you are hitting the recommended quota and will the reasons given above help make it easier to consume?


  1. Just started back on S&S I lost 2 & 1/2 stone las October but the weight crept back on – I aim to lose 2 stones in weight. Water is the key to this success.

  2. I find the topic of water some what amusing… unless of course I’m doing something dreadfully wrong. I started back on my Slim & Save diet on the 28th May in the first week back I’d lost 19lb. For sure, I did find the water a problem to begin with, but then I bought a 3.78 ltr water bottle off Amazon and I carry a 700ml & 2x 600ml bottles with me. They all start off full, then I refill my 700ml bottle from the 3.78ml bottle and I get through it all.

    This may sound like a lot to those of you having to drink 3 ltrs but I am or was weighing in at 23 stone and my water intake was 5.2 ltrs. Of course having lost 19 lb my water intake indicator has dropped to 4.8 ltrs but in all honesty since purchasing the bottles I find it so easy to consume all this water gradually throughout the day… so I’ve just carried on with it. Last Wednesday I… you wouldn’t believe how much I drank, haha.

    Headaches? I’ve had none. I think the secret is simply… Fill your bottles and then just stop thinking about it. Get on with your day and those bottles will disappear along with 🙂 the weight 🙂

    I can’t thank Slim & Save enough.

  3. I too have always struggled to drink water – black coffee I drink plenty of! But of course this doesn’t count!
    However ketosis makes me so thirsty I crave the water! Having a refillable 750ml water bottle with me all the time really helps – I just twist and Click the lid each time I fill up and a dot appears. This makes it easy to monitor how much I have drunk. I also use the food planner with the water ‘meter’ at the side – handy!.
    I’m loving the water flavourings too for those times when just plain water is just not enough and helps with hunger pangs!

  4. I think is quite easy if im honest at breakfast i have 2 cups of coffee thats 800ml
    1 glass of water thats 400ml
    then my pack 240ml
    mid morning coffee 400ml
    lunch soup 400ml
    then my evening meal 150ml
    & with extra drinks aswell i may reach 3L
    its not that scary it would be if the packs weren’t included though! i would never make it LOL

  5. Iv also been a Diet Coke and coffee kinda girl. I worried starting the plan that I would struggle with this and only drinking water. I’m on day 5 and I am drinking 3L a day of water. I like it cold and refreshing and in my reusable plastic bottle so I’m helping climate change at the same time! I do live in care my clients gets to drink anything they would like I have temptation all around me however having my bottle of water has made things a lot easier for me I take a few sips whenever needed I finish my bottle and I fill it up again- I wrote down each day how much fluid I have to keep on top of it all and to make sure I’m not at risk of dehydrating. My skin is glowing it’s also feeling smoother and tighter. Water is also filling so if I do feel like a snack I drink my water instead.

  6. I will admit that before starting this diet I can’t really remember ever drinking water. My fluid intake generally was poor and mostly involved diet fizzy drinks and constant cups of coffee.

    From day 1 of starting SNS I have drank 2-3 litres of water and have been surprised at the difference. I have more energy, less headaches, sleep better and my skin is looking brighter. It also is a great tool to reduce any hunger pangs.
    I am not good at drinking plain water from a glass, but discovered if I use a reusable water bottle it is much easier to keep sipping throughout the day and keep an eye on quantity.

  7. I agree. I tend to be guided by my thirst and I do drink at least 3 litres a day. I think it really helps the headaches through the first week or so and my skin looks and feels so much better.

  8. I’am (73) and trying to get back to my gorgeous bikini body.Ha!Ha!.I did it a few years ago with Slim & Save, but sadly fell by the wayside.I have never been a fan of water but understand the need to drink more than I normally do, little and often is the secret. Keep Your fingers crossed for me. Thank you Slim & Save

  9. I love my water bottle with timings on it, makes drinking my quota seem so much more achievable. I drink 1.5l during the day at work then at least another 1l in the evening and that’s not including what I put in my packs. I also love the water flavourings in sparkling water on an evening – especially the white wine and the orange (tastes just like Fanta)

  10. I found that drinking more water definitely improves weight loss but also better skin and hair. I aim to drink 2-3l a day but use water tracker apps and my warrr bottle measurer to keep me motivated. Kind of like setting myself a challenge! I’m not one to be beaten! I always drink a pint of water before a meal to check I am really hungry and to keep me full longer!

  11. I start plan tomorrow and am aiming for minimum 2L each day. I’ve always struggled with water intake but once you get into the habit of it it becomes much easier.

  12. I love a cup of hot water in the morning! My office gets cold too so sometimes I swap out a cold glass for a hint one to warm up my hands! Definitely great for weight loss. WATER: Drink to Shrink

  13. At first it was difficult to drink the recommended amount of water but I have got used to it now. I have a refillable water bottle that I keep with me everywhere I go so I can keep hydrated. The comments on the group about the more you drink the better the weight loss really spur me on. Previously I wasn’t a great water drinker but now it has become normal and I no longer drink the amount of tea and coffee I used to. Most days I drink the level I should for my weight. Plumping up the skin to reduce my wrinkles is a bonus.

  14. Thanks for those well explained details Annemarie. Lots of useful facts to keep us motivated. I make a pot of tea every morning. That’s 3 large mugs of water to get my day started with a boost of hydration. I naturally want to drink much more than my recommended litres when I am on holiday in a hot country, but I space this out so that I don’t drink more than 1 litre in an hour.

  15. I have a water bottle holding 700ml and I always have it with me. I try to drink the recommended water intake. Sometimes it is hard but thinking about the benefits and reading posts from other SNS users remarking on the affect it has on their weight loss spurs me on. I didn’t really drink much water before using this plan but now it has become second nature.

  16. I totally agree – in the past, I have been a bit lax with my water consumption but on this re-start I have been meticulous, making sure I drink the recommended amount. I feel so much better in myself and am not suffering from any nasty side effects of being in ketosis.

    The water calculator on the Meal Planner is an excellent tool, I use it every day.

  17. Water is obviously very important considering we are mainly made up with a fair bit of the stuff!
    I always fill my water bottle in the morning and again in the afternoon. Throughout the day, I drink a good few cups of peppermint tea which I also drink in the evening. I think I easily drink the recommended 2-3 litres.
    It’s also worth knowing, our bodies can think we are hungry when in fact it’s thirst.

  18. I always drink lots of water. I am lucky to live in Fife and our tap water tastes better than any Spring Spa bottled water. I always carry water for me and my Therapet dog Jilli.

  19. I’ve just gone back on slim and save after a two-year break due to an accident. I’ve been drinking lots of water and already I’m sleeping better my skins looks fresh and I’m starting to feel myself again I’m motivated to lose the weight because I’ve got a holiday in August an looking forward to buying smaller size clothes I know the programme works because I’ve done it before thank you slim and save.

Leave a Reply